High pressure seal back-up

ABSTRACT

A seal mechanism for use with a downhole component comprises a first tubular member and a second tubular member, wherein the first tubular member is disposed within the second tubular member and separated therefrom by an extrusion gap; a circumferential groove disposed on the first tubular member; a seal disposed within the circumferential groove, wherein the seal is selectively positionable into engagement with the second tubular member; and a high pressure seal back-up disposed within the circumferential groove, wherein the distance between an inside diameter of the high pressure seal back-up and an outside diameter of the high pressure seal back-up is configured to remain substantially constant when pressure increases on the high pressure seal back-up, and wherein the high pressure seal back-up is configured to have an increase in its outer diameter in response to a pressure increase.

CROSS-REFERENCE TO RELATED APPLICATIONS

None.

STATEMENT REGARDING FEDERALLY SPONSORED

RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

BACKGROUND

The field of the invention relates to seal back-ups for wellbore toolsoften used in oil and gas well applications. Sealing members engagemovable members in wellbore tools. Seal back-ups provide support for thesealing members as well as attempt to reduce an extrusion gap. Whenunder pressure, sealing members can extend through the extrusion gapwhen making sealing contact. During this time, standard seals can fallthrough the extrusion gap and limit the amount of the seal surface areaengaging an outer surface to form a sealing engagement. Additionally,standard seals can shear and cause fragments of the seal to fall throughthe extrusion gap (often called the nibbling effect). Over time,prolonged nibbling can cause premature failure of the seal.

SUMMARY

In an embodiment, a seal mechanism for use with a downhole componentcomprises a first tubular member and a second tubular member, whereinthe first tubular member is disposed within the second tubular memberand separated therefrom by an extrusion gap; a circumferential groovedisposed on the first tubular member; a seal disposed within thecircumferential groove, wherein the seal is selectively positionableinto engagement with the second tubular member; and a high pressure sealback-up disposed within the circumferential groove, wherein the distancebetween an inside diameter of the high pressure seal back-up and anoutside diameter of the high pressure seal back-up is configured toremain substantially constant when pressure increases on the highpressure seal back-up, and wherein the high pressure seal back-up isconfigured to have an increase in its outer diameter in response to apressure increase.

In an embodiment, a high pressure seal mechanism for use with a downholecomponent in a wellbore environment comprises a tubular member and asurface, where the tubular member is disposed adjacent to the surfaceand separated from the surface by an extrusion gap, a circumferentialgroove disposed on the tubular member, a seal disposed within thecircumferential groove, where the seal is selectively positionable intoan engagement with the surface, and a high pressure seal back-updisposed within the circumferential groove, where the distance betweenan inside diameter of the high pressure seal back-up and an outsidediameter of the high pressure seal back-up is configured to remainsubstantially constant when pressure increases on the high pressure sealback-up.

In another embodiment, a method comprises increasing pressure on a sealand a high pressure seal back-up, where the seal and high pressure sealback-up are disposed with a circumferential groove, extending the highpressure seal back-up into an extrusion gap, and forming a seal betweena tubular member and a surface.

These and other features will be more clearly understood from thefollowing detailed description taken in conjunction with theaccompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and theadvantages thereof, reference is now made to the following briefdescription, taken in connection with the accompanying drawings anddetailed description:

FIG. 1 is a cut-away view of an embodiment of a wellbore servicingsystem.

FIG. 2A is a side view of an embodiment of a high pressure sealmechanism.

FIG. 2B is a cross-section view of an embodiment of a high pressure sealmechanism.

FIG. 3A is a side view of an embodiment of a high pressure seal back-up.

FIG. 3B is a side view of an embodiment of a standard seal back-up.

FIG. 4A is another cross-section view of an embodiment of a highpressure seal mechanism.

FIG. 4B is cross-section view of an embodiment of a high pressure sealback-up.

FIG. 5A is a cross-section view of an embodiment of a standard sealmechanism.

FIG. 5B is a cross-section view of an embodiment of a seal in a standardseal mechanism.

FIG. 5C is cross-section view of an embodiment of a standard sealback-up and a seal in a standard seal mechanism.

FIG. 6 is another cross-section view of an embodiment of a high pressureseal mechanism.

FIG. 7 is another cross-section view of an embodiment of a high pressureseal mechanism.

FIG. 8 is another cross-section view of an embodiment of a high pressureseal mechanism.

FIG. 9 is another cross-section view of an embodiment of a high pressureseal mechanism.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the drawings and description that follow, like parts are typicallymarked throughout the specification and drawings with the same referencenumerals, respectively. The drawing figures are not necessarily toscale. Certain features of the invention may be shown exaggerated inscale or in somewhat schematic form and some details of conventionalelements may not be shown in the interest of clarity and conciseness.Specific embodiments are described in detail and are shown in thedrawings, with the understanding that the present disclosure is to beconsidered an exemplification of the principles of the invention, and isnot intended to limit the invention to that illustrated and describedherein. It is to be fully recognized that the different teachings of theembodiments discussed infra may be employed separately or in anysuitable combination to produce desired results.

Unless otherwise specified, any use of any form of the terms “connect,”“engage,” “couple,” “attach,” or any other term describing aninteraction between elements is not meant to limit the interaction todirect interaction between the elements and may also include indirectinteraction between the elements described. In the following discussionand in the claims, the terms “including” and “comprising” are used in anopen-ended fashion, and thus should be interpreted to mean “including,but not limited to . . . ”. Reference to up or down will be made forpurposes of description with “up,” “upper,” “upward,” or “upstream”meaning toward the surface of the wellbore and with “down,” “lower,”“downward,” or “downstream” meaning toward the terminal end of the well,regardless of the wellbore orientation. Reference to in or out will bemade for purposes of description with “in,” “inner,” or “inward” meaningtoward the center or central axis of the wellbore, and with “out,”“outer,” or “outward” meaning toward the wellbore tubular and/or wall ofthe wellbore. Reference to “longitudinal,” “longitudinally,” or“axially” means a direction substantially aligned with the main axis ofthe wellbore and/or wellbore tubular. Reference to “radial” or“radially” means a direction substantially aligned with a line betweenthe main axis of the wellbore and/or wellbore tubular and the wellborewall that is substantially normal to the main axis of the wellboreand/or wellbore tubular, though the radial direction does not have topass through the central axis of the wellbore and/or wellbore tubular.The various characteristics mentioned above, as well as other featuresand characteristics described in more detail below, will be readilyapparent to those skilled in the art with the aid of this disclosureupon reading the following detailed description of the embodiments, andby referring to the accompanying drawings.

Several tools used in a servicing operation may comprise one or morehigh pressure seal mechanisms configured to engage one or more othercomponents. For example, a completion tool and/or a retrieval tool maycomprise a piston having a high pressure seal mechanism. The componentmay be fixedly attached to the tool. A tool comprising a high pressureseal mechanism may comprise a seal to engage a surface in the wellbore.This seal may be disposed in a circumferential groove, and thecircumferential groove may be disposed circumferentially on a surface ofa portion of the wellbore tool. Traditional seal back-ups may be used inseals to help maintain the seal under high pressure. However,traditional back-ups do not extend into the extrusion gap, leading topotential leaks and loss of integrity of the seal. In order to addressthis potential problem, the high pressure seal back-up disclosed hereinextends into the extrusion gap under pressure, supporting the seal inthe extrusion gap when the seal is under pressure. The high pressureseal mechanism may comprise a high pressure seal back-up disposed withthe circumferential groove and configured so that the distance betweenthe inside diameter of the high pressure seal back-up and the outsidediameter of the high pressure seal back-up remain substantially constantwhen pressure increases on the high pressure seal back-up. As usedherein, “high pressure” means greater than or equal to about 500 poundsper square inch, greater than or equal to about 1,000 pounds per squareinch, greater than or equal to about 5,000 pounds per square inch, orgreater or equal to about 10,000 pounds per square inch. One of ordinaryskill in the art would understand, with the aid of this disclosure, whena “high pressure” scenario exists based on, for example, the operationalconditions, the service environment, the type of seal, or any safetyconcerns. For example, a “high pressure” scenario may exist, which mayrequire a high pressure seal back-up, when there is a need for astandard seal back-up. While described in terms of a high pressure sealback-up and a high pressure seal system in some embodiments, the systemsand methods described herein may also be used at pressures less thanthose considered high pressure.

When the high pressure seal mechanism is under high pressure, the sealextends from the groove, into the extrusion gap, and engages an outsidesurface. The high pressure seal back-up may also extend from the grooveand into the extrusion gap. The high pressure seal back-up may engagethe seal in the extrusion gap, supporting the seal in the extrusion gap,and preventing the seal from falling into the extrusion gap. Preventingthe seal from falling into the extrusion gap facilitates a bettersealing engagement between the tool and outside surface. Additionally,this feature may also relieve pressure between the seal and the edge of,for example, the circumferential groove or a second seal back-up,reducing any shear force on the seal, and potentially extending the lifeof the seal.

As further disclose herein, the high pressure sealing mechanism maycomprise a plurality of second seal back-ups and a plurality of highpressure seal back-ups. The plurality of second seal back-ups and theplurality of high pressure seal back-ups provide support for the seal inthe circumferential groove. In one embodiment, a plurality of secondseal back-ups and a plurality of high pressure seal back-ups areconfigured to make the high pressure seal mechanism a two-way seal. Inanother embodiment, a plurality of second seal back-ups and a pluralityof high pressure seal back-ups are configured to make the high pressureseal mechanism a one-way seal. Additionally, the high pressure sealback-up may have a plurality of locking teeth extending outwardly fromthe high pressure seal back-up and configured to engage with a pluralityof locking teeth extending outwardly from a surface adjacent to the highpressure seal back-up. In some embodiments, a wedge may be fixedlyattached to a surface adjacent to the high pressure seal back-up. Thesefeatures may limit the reduction of the outside diameter of the highpressure seal back-up when pressure decreases on the high pressure sealback-up. Further features may keep the high pressure seal back-up in theextrusion gap when, for example, there is a sudden drop in differentialpressure followed quickly by a rise in differential pressure whereotherwise the seal might fall into the extrusion gap before the highpressure seal back-up has time to move back into the extrusion gap andprevent the seal from falling through the extrusion gap.

Turning to FIG. 1, an example of a wellbore operating environment inwhich one or more high pressure seal mechanisms may be used is shown. Asdepicted, the operating environment comprises a drilling rig 106 that ispositioned on the earth's surface 104 and extends over and around awellbore 114 that penetrates a subterranean formation 102 for thepurpose of recovering hydrocarbons. The wellbore 114 may be drilled intothe subterranean formation 102 using any suitable drilling technique.The wellbore 114 extends substantially vertically away from the earth'ssurface 104 over a vertical wellbore portion 116, deviates from verticalrelative to the earth's surface 104 over a deviated wellbore portion136, and transitions to a horizontal wellbore portion 118. Inalternative operating environments, all or portions of a wellbore may bevertical, deviated at any suitable angle, horizontal, and/or curved. Thewellbore may be a new wellbore, an existing wellbore, a straightwellbore, an extended reach wellbore, a sidetracked wellbore, amulti-lateral wellbore, and other types of wellbores for drilling andcompleting one or more production zones. Further the wellbore may beused for both producing wells and injection wells. In an embodiment, thewellbore may be used for purposes other than or in addition tohydrocarbon production, such as uses related to geothermal energy and/orthe production of water (e.g., potable water).

A wellbore tubular string comprises a seal mechanism may be lowered intothe subterranean formation 102 for a variety of drilling, completion,workover, and/or treatment procedures throughout the life of thewellbore. The embodiment shown in FIG. 1 illustrates the wellboretubular 120 in the form of a completion string being lowered into thesubterranean formation. It should be understood that the wellboretubular 120 is equally applicable to any type of wellbore tubular beinginserted into a wellbore, including as non-limiting examples drill pipe,production tubing, rod strings, and coiled tubing. In the embodimentshown in FIG. 1, the wellbore tubular 120 comprising the high pressureseal mechanism may be conveyed into the subterranean formation 102 in aconventional manner and may subsequently be used to provide a sealwithin the wellbore as described herein.

The drilling rig 106 comprises a derrick 108 with a rig floor 110through which the wellbore tubular 120 extends downward from thedrilling rig 106 into the wellbore 114. The drilling rig 106 comprises amotor driven winch and other associated equipment for extending thewellbore tubular 120 into the wellbore 114 to position the wellboretubular 120 at a selected depth. While the operating environmentdepicted in FIG. 1 refers to a stationary drilling rig 106 for loweringand setting the wellbore tubular 120 comprising the seal mechanismwithin a land-based wellbore 114, in alternative embodiments, mobileworkover rigs, wellbore servicing units (such as coiled tubing units),and the like may be used to lower the wellbore tubular 120 comprisingthe seal mechanism into a wellbore. It should be understood that awellbore tubular 120 comprising the seal mechanism may alternatively beused in other operational environments, such as within an offshorewellbore operational environment. In alternative operating environments,a vertical, deviated, or horizontal wellbore portion may be cased andcemented and/or portions of the wellbore may be uncased.

Regardless of the type of operational environment in which the highpressure seal mechanism 200 is used, it will be appreciated that thehigh pressure seal mechanism 200 serves to provide a seal between twocomponents. The high pressure seal mechanism 200 may utilize differentconfigurations than a standard seal mechanism. As described in greaterdetail below with respect to FIGS. 2A and 2B, the high pressure sealmechanism 200 generally comprises a first tubular member 202 and asecond tubular member 204, a circumferential groove 206, a seal 208, anda high pressure seal back-up 210. The circumferential groove 206 isdisposed on the first tubular member 202. The first tubular member 202and second tubular member 204 are separated by an extrusion gap 212. Theseal 208 may be disposed within the circumferential groove 206 so thatthe seal 208 is selectively positionable into engagement with the secondtubular member 204. The high pressure seal back-up 210 may be disposedat least partially within the circumferential grove 206 so that whenpressure increases on the high pressure seal back-up 210 the outerdiameter of the high pressure seal back-up 210 increases while thedistance between an inside diameter of the high pressure seal back-up210 and an outside diameter of the high pressure seal back-up 210 remainsubstantially constant.

FIG. 2A illustrates a side view of the high pressure seal mechanism 200,and FIG. 2B illustrates the same embodiment of the high pressure sealmechanism 200 in cross-section. As shown in FIGS. 2A and 2B, anembodiment of the high pressure seal mechanism 200 comprises a firsttubular member 202 and a second tubular member 204, the first tubularmember 202 and the second tubular member 204 are separated by anextrusion gap 212. The second tubular member 204 may also be a flatsurface, a surface such as a bore, (e.g., in a wall of a component,within a tubular member, etc.) or any other type of surface as long asan extrusion gap 212 exists between the first tubular member 202 and thesecond tubular member 204. A circumferential groove 206 is disposed onthe first tubular member 202. The circumferential groove 206 may bedisposed radially, for example, on the first tubular member 202 suchthat the circumferential groove 206 extends perpendicular to thelongitudinal axis of the first tubular member 202. In an embodiment, thecircumferential groove 206 may extend at a non-perpendicular angle tothe longitudinal axis of the first tubular member 202. In an embodiment,the circumferential groove 206 may also be disposed elliptically, forexample, such that the distance from the center point of thecircumferential groove 206 on the longitudinal axis of the first tubularmember 202 to the circumferential groove 206 is not constant.

A seal 208 is disposed with the circumferential groove 206. The seal 208may be an o-ring, for example, or it may be any other member that couldprovide a seal between the first tubular member 202 and the secondtubular member 204. The seal 208 may rest inside, on, or adjacent to thecircumferential groove 206. When pressure is not applied, the seal 208may sit inside the circumferential groove 206 without extending radiallyinto the extrusion gap 212, the seal 208 may at least partially extendinto the extrusion gap 212, or the seal 208 may engage the secondtubular member 204.

A high pressure seal back-up 210 is disposed with the circumferentialgroove 206. The high pressure seal back-up 210 may rest inside, on, oradjacent to the circumferential groove 206. When pressure is notapplied, the high pressure seal back-up 210 may sit inside thecircumferential groove 206 without extending radially into the extrusiongap 212, or the high pressure seal back-up 210 may at least partiallyextend radially into the extrusion gap 212. As shown in FIG. 3A and FIG.3B, an embodiment of the high pressure seal back-up 210, depicted inFIG. 3A, depicts how the high pressure seal back-up 210 has two mainfaces that generally face in the direction that a normal force would beapplied as shown. The main faces of the high pressure seal back-up 210are such that they are located on at least two planes which intersectwhen pressure is not applied to the main faces of the high pressure sealback-up 210. When under pressure, the high pressure seal back-up 210 maypartially flatten out and radially expand. In an embodiment, the highpressure seal back-up 210 may at radially expand by at least about 1%,at least about 2%, at least about 3%, at least about 4%, at leastabout5%, at least about 6%, at least about 7%, at least about 8%, atleast about 9%, or at least about 10% of the outer radius of the highpressure seal back-up 210 in an uncompressed and un-expanded state. Inan embodiment, the inside and outside diameters of the high pressureseal back-up 210 may increase when axially compressed. When underpressure, the high pressure seal back-up 210 may flatten out and theinside and outside diameters of the high pressure seal back-up 210 mayincrease. This feature of the high pressure seal back-up 210 allows thedistance between an inside diameter of the high pressure seal back-up210 and an outside diameter of the high pressure seal back-up 210 toremain substantially constant when the high pressure seal back-up 210 isunder high pressure. In an embodiment of the high pressure seal back-up210, the high pressure seal back-up 210 comprises a wave spring, whichcan comprise any ring having one or more wave-like features and/orradially expands upon being axially compressed.

Conversely, FIG. 3B depicts how a standard seal back-up has two mainfaces that generally face in the direction that a normal force would beapplied as shown. However, the main faces of the standard seal back-upare such that they are located on parallel planes. In thisconfiguration, the outside and inside diameter of the high pressure sealback-up 210 remain substantially constant even when a load is applied.This configuration relies more heavily on the elastic or inelasticmalleable characteristics of its composition under a normal force.

The various components of the sealing mechanism (e.g., the high pressureseal back-up) may be formed from materials selected to withstanddownhole conditions including heat and/or various acidic or basicfluids. Examples of suitable materials may include, but are not limitedto, fluoropolymers, polyethylene polymers, silicone polymers, urethanepolymers, and any combination thereof. Nonlimiting examples of suitableelastomeric compounds include, ethylene propylene diene monomer (EPDM),fluoroelastomers (FKM) [Viton®], perfluoroelastomers (FFKM) [Kalrez®,Chemraz®, Zalak®], flouoropolymer elastomers [Viton®],polytetrafluoroethylene, copolymer of tetrafluoroethylene and propylene(FEPM) [Aflas®], and polyetheretherketone (PEEK), polyetherketone (PEK),polyamide-imide (PAI), polyimide [Vespel®], polyphenylene sulfide (PPS),and any combination thereof. In addition to these components, variousmetals suitable for use in forming the high pressure seal back-up may beused (e.g., spring steel and the like). In an embodiment, metals thatexperience plastic deformation may be used when, for example, the sealback-up does not need to act as a dynamic seal. Various other componentsmay be used in combination with any of the listed materials.

As shown in FIG. 4A, another embodiment of the high pressure sealmechanism 200 depicts the high pressure seal mechanism 200 under apressure differential. In this embodiment, the seal 208 acting under anormal force created by the differential pressure (e.g., a higherpressure on the right of the seal 208 than on the left of the seal 208in FIG. 4A) extends into the extrusion gap 212 engaging the secondtubular member 204. Additionally, the high pressure seal back-up 210acting under a normal force created by the differential pressure expandsand extends into the extrusion gap 212 while keeping the distancebetween the inside diameter of the high pressure seal back-up 210 andthe outside diameter of the high pressure seal back-up 210 substantiallyconstant relative to the distance between the inside diameter of thehigh pressure seal back-up 210 and the outside diameter of the highpressure seal back-up 210 when pressure is not applied. As a normalforce is applied to the high pressure seal back-up 210, the insidediameter of the high pressure seal back-up 210 begins to move a distance404 from the base of circumferential groove 206. At the same time, theoutside diameter of the high pressure seal back-up 210 begins to move adistance 404 into the extrusion gap. As a normal force is applied to thehigh pressure seal back-up 210 the distances 402 and 404 aresubstantially the same. The high pressure seal back-up 210 engages boththe wall of the circumferential groove 206 and the seal 208. Thisfeature prevents the seal 208 from falling through the extrusion gap 212and engages more surface area of the seal 208 with the second tubularmember 204 creating a stronger seal, as more closely shown in FIG. 4B.This feature also substantially reduces the shearing and nibbling effecton the seal 208 by preventing the seal 208 from falling through theextrusion gap 212 and shearing the seal 208 with an edge. In anotherembodiment, the high pressure seal back-up 210 may also engage thesecond tubular member 204.

As shown in FIG. 5A, another embodiment depicts the effect a standardseal mechanism 500 has on a seal 508 under a pressure differential. Inthis embodiment, the seal 508 is allowed to extend through the extrusiongap 512 reducing the engagement that could take place between the seal508 and the second tubular member 204, as shown in FIG. 5B, and shearingthe seal 508 producing a nibbling effect that accelerates the wear onthe seal 508, as shown in FIG. 5B. Unlike the high pressure seal back-up210 in FIG. 4A, the standard seal back-up 514 depicted in FIG. 5A andFIG. 5B relies more heavily on the elastic or inelastic malleablecharacteristics of its composition under a normal force and does notsubstantially extend into the extrusion gap 512. Thus, the standardback-up seal 514 may not be as effective at preventing the seal 508 fromfalling through the extrusion gap 512 as the high pressure seal back-updescribed herein.

As shown in FIG. 6, another embodiment discloses a second seal back-up614 disposed adjacent to the seal 608 and adjacent to the high pressureseal back-up 610. Although in this embodiment the second seal back-up614 is disposed between the high pressure seal back-up 610 and the seal608, the second seal back-up 614 may also be positioned on lowerpressure side from the high pressure seal back-up 610, a higher pressureside from the seal 608, or anywhere disposed with the circumferentialgroove 606. This configuration provides extra support in thecircumferential groove 606 for the high pressure seal back-up 610 andthe seal 608 and helps to provide a uniform force on the high pressureseal back-up 610 helping to uniformly compress the high pressure sealback-up 610 in the axial direction. In this embodiment, even though thesecond seal back-up 614 has a corner that appears to be similar to thecorner depicted in FIG. 5 and FIG. 5B that would result in the nibblingeffect, the high pressure seal back-up 610 still prevents the seal 610from falling through the extrusion gap 612 and thus greatly reduces theshearing between the second seal back-up 614 and the seal 608.

As shown in FIG. 7, another embodiment discloses the use of a pluralityof high pressure seal back-ups 710 as well as a plurality of second sealback-ups 714. This configuration provides extra support for the seal 708in the circumferential groove 706. The positions of the seal 708, theplurality of high pressure seal back-ups 710, and the plurality ofsecond seal back-ups 714 may be disposed in any combination with thecircumferential groove 706. Furthermore, in this embodiment and othersimilar embodiments the high pressure seal mechanism 700 may be atwo-way seal. In general, a two-way seal comprises a seal configured tomaintain a pressure differential in a first direction that issubstantially similar to a pressure differential in a second direction.In other embodiments, the high pressure seal mechanism may be a one-wayseal. In general, a one-way seal comprises a seal configured to maintaina first pressure differential in a first direction and a seconddifferential in a second direction, where the first pressuredifferential and the second pressure differential are different. Forexample, when a high pressure seal back-up is disposed on only one sideof a seal, the seal may maintain a seal at a higher pressuredifferential when the higher pressure is applied to the seal side thanwhen the higher pressure is applied to the high pressure seal back-upside. When the pressure is applied to the high pressure seal back-upside, the pressure may bias the high pressure seal back-up away from thewall of the groove and not axially compress the high pressure sealback-up.

As shown in FIG. 8, another embodiment discloses a plurality of lockingteeth 816 extending outwardly from the high pressure seal back-up 810and configured to engage with a plurality of locking teeth 816 extendingoutwardly from a surface adjacent to the high pressure seal back-up 810.FIG. 8 depicts the plurality of locking teeth 816 engaging the highpressure seal back-up 810 with the second seal back-up 814. However, theplurality of locking teeth 818 may engage the high pressure seal back-up810 with any surface disposed with the circumferential groove 806including the wall of the circumferential groove 806. The plurality oflocking teeth 816 are configured to limit the reduction of the outsidediameter of the high pressure seal back-up 810 when pressure decreases.This configuration keeps the high pressure seal back-up 810 in theextrusion gap 812 when, for example, there is a sudden drop indifferential pressure followed quickly by a rise in differentialpressure where otherwise the seal 808 might fall into the extrusion gap812 before the high pressure seal back-up 810 has time to move back intothe extrusion gap 812 and prevent the seal 808 from falling through theextrusion gap 812. When pressure decreases across the high pressure sealmechanism 800, the plurality of locking teeth 816 prolong the time thehigh pressure seal back-up 810 remains extended into the extrusion gap812 before the high pressure seal back-up 810 resets into the lowpressure condition. When the high pressure seal back-up 810 axiallyexpands, it may no longer fully engage the locking teeth 816 and mayeventually disengage from the locking teeth 816 upon a sufficient amountof axial expansion. Once the plurality of locking teeth 816 are nolonger engaged, the high pressure seal back-up 810 contracts into thecircumferential grove 806 and into the low pressure condition.

As shown in FIG. 9, another embodiment discloses a wedge 918 fixedlyattached to a second surface adjacent to the high pressure seal back-up910 and configured to limit the reduction on the outside diameter of thehigh pressure seal back-up 910 when pressure decreases on the highpressure seal back-up 910. FIG. 9, depicts the wedge 918 fixedlyattached to a second seal back-up 914, however, the wedge 918 can befixedly attached to any surface disposed with the circumferential groove906 and adjacent to the high pressure seal back-up 910. The wedgeconfiguration keeps the high pressure seal back-up 910 in the extrusiongap 912 when, for example, there is a sudden drop in differentialpressure followed quickly by a rise in differential pressure whereotherwise the seal 908 might fall into the extrusion gap 912 before thehigh pressure seal back-up 910 has time to move back into the extrusiongap 912 and prevent the seal 908 from falling through the extrusion gap912. When pressure decreases across the high pressure seal mechanism900, the wedge 918 prolongs the time the high pressure seal back-up 910remains extended into the extrusion gap 912 before the high pressureseal back-up 910 resets into the low pressure condition. When the highpressure seal back-up 910 axially expands, it may no longer fully engagethe wedge 918 and may eventually disengage from the wedge 918 upon asufficient amount of axial expansion. Once the wedge 918 no longerengages the high pressure seal back-up 910, the high pressure sealback-up 910 contracts into the circumferential grove 906 and into thelow pressure condition.

A seal mechanism may be assembled using any technique known in the art.In an embodiment, the seal mechanism may be assembled by firstconstructing the seal mechanism on the first tubular member. Acircumferential groove may be disposed on the first tubular member and aseal may be disposed at least partially within the circumferentialgroove. For example, the seal may comprise an elastomeric material thatmay be stretched and passed over the first tubular member beforecontracting into the groove A high pressure seal back-up may be disposedat least partially within the circumferential groove by compressing thehigh pressure seal back-up to radially expand both the inner and outerdiameters, placing the high pressure seal back-up around the axis of thefirst tubular member so that the first tubular member fits through theinside diameter of the high pressure seal back-up, moving the highpressure seal back-up along the axis of first tubular member until it isradially positioned with the circumferential groove, and decompressingthe high pressure seal back-up allowing the inside diameter of the highpressure seal back-up to contract. The first tubular member may then bedisposed within the second tubular member. As an alternative tocompressing the high-pressure seal back-up during installation, a cut(e.g., a radial cut) may be made in the high pressure seal back-up tocreate a gap in the high pressure seal back-up to allow the highpressure seal back-up to expand. The high pressure seal back-up may thenbe moved over the first tubular member. Once the high pressure sealback-up is radially in position with the circumferential groove, thehigh pressure seal back-up gap may contract, reducing the diameter ofthe high pressure seal back-up, and positioning the high pressure sealback-up at least partially within the circumferential groove. Thefurther axial compression of the high pressure seal back-up during usemay serve to close the cut.

In an embodiment, the seal mechanism may be used to form a seal betweentwo surfaces. The pressure on the seal and the high pressure sealback-up may be increased when the seal and the high pressure sealback-up are disposed at least partially within the circumferentialgroove. The high pressure seal back-up may be extended into theextrusion gap, and the seal may engage a tubular member and a surface toform a sealing engagement between the tubular member and the surface.The high pressure seal back-up may extend into extrusion gap in responseto an axial compression, which may result from the application of apressure differential across the seal mechanism. As the high pressureseal back-up expands, the distance between an inside diameter of thehigh pressure seal back-up and an outside diameter of the high pressureseal back-up may remain substantially constant. The seal mechanism maythen maintain a seal while the pressure differential is maintainedacross the seal mechanism. In an embodiment, the high pressure sealback-up may extend into the extrusion gap and contact the surface,thereby forming an engagement between both the tubular member and thesurface. In some embodiments, locking teeth may be used. In thisconfiguration, the locking teeth on the high pressure seal back-up mayengage the corresponding features on an adjacent surface (which maycomprise one-way features), thereby preventing the high pressure sealback-up from radially contracting until the pressure differential hasfallen below a threshold. In some embodiments, a wedge disposed on anadjacent surface to the high pressure seal back-up may be used. In thisconfiguration, the wedge on the adjacent surface may engage the highpressure seal back-up, thereby preventing the high pressure seal back-upfrom radially contracting until the pressure differential has fallenbelow a threshold.

When the pressure differential across the seal mechanism decreases, thehigh pressure seal back-up may radially contract away from the surfacewhile maintaining a substantially constant distance between an outsidediameter of the high pressure seal back-up and an inside diameter of thehigh pressure seal back-up. In an embodiment, the high pressure sealback-up may contract out of the extrusion gap. When a wedge is used onan adjacent surface to the high pressure seal back-up, the wedge mayslow the reduction of the outside diameter of the high pressure sealback-up when pressure decreases on the high pressure seal back-up.Similarly when one or more locking features are used on an adjacentsurface to the high pressure seal back-up, the locking features may slowthe reduction of the outside diameter of the high pressure seal back-upwhen pressure decreases on the high pressure seal back-up. Once thepressure differential across the seal mechanism has fallen below athreshold, the high pressure seal back-up may axially expand anddisengage from any locking features, thereby allowing the high pressureseal back-up to contract into the circumferential groove. Thepressurization/depressurization cycle may be repeated any number oftimes and the seal mechanism may be used to form a seal across theextrusion gap.

At least one embodiment is disclosed and variations, combinations,and/or modifications of the embodiment(s) and/or features of theembodiment(s) made by a person having ordinary skill in the art arewithin the scope of the disclosure. Alternative embodiments that resultfrom combining, integrating, and/or omitting features of theembodiment(s) are also within the scope of the disclosure. Wherenumerical ranges or limitations are expressly stated, such expressranges or limitations should be understood to include iterative rangesor limitations of like magnitude falling within the expressly statedranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4,etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example,whenever a numerical range with a lower limit, R₁, and an upper limit,R_(u), is disclosed, any number falling within the range is specificallydisclosed. In particular, the following numbers within the range arespecifically disclosed: R=R₁k*(*(R_(u)-R₁), wherein k is a variableranging from 1 percent to 100 percent with a 1 percent increment, i.e.,k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . , 50percent, 51 percent, 52 percent, . . . , 95 percent, 96 percent, 97percent,98 percent, 99 percent, or 100 percent. Moreover, any numericalrange defined by two R numbers as defined in the above is alsospecifically disclosed. Use of the term “optionally” with respect to anyelement of a claim means that the element is required, or alternatively,the element is not required, both alternatives being within the scope ofthe claim. Use of broader terms such as comprises, includes, and havingshould be understood to provide support for narrower terms such asconsisting of, consisting essentially of, and comprised substantiallyof. Accordingly, the scope of protection is not limited by thedescription set out above but is defined by the claims that follow, thatscope including all equivalents of the subject matter of the claims.Each and every claim is incorporated as further disclosure into thespecification and the claims are embodiment(s) of the present invention.

What is claimed is:
 1. A seal mechanism for use with a downholecomponent comprising: a first tubular member and a second tubularmember, wherein the first tubular member is disposed within the secondtubular member and separated therefrom by an extrusion gap; acircumferential groove disposed on the first tubular member; a sealdisposed within the circumferential groove, wherein the seal isselectively positionable into engagement with the second tubular member;and a high pressure seal back-up disposed within the circumferentialgroove, wherein the distance between an inside diameter of the highpressure seal back-up and an outside diameter of the high pressure sealback-up is configured to remain substantially constant when pressureincreases on the high pressure seal back-up, wherein the high pressureseal back-up is configured to have an increase in its outer diameter inresponse to a pressure increase, and wherein the high pressure sealback-up is a wave spring.
 2. The seal mechanism of claim 1, wherein aplurality of locking teeth are disposed on a surface of the highpressure seal back-up and are configured to engage with a plurality oflocking teeth disposed on a surface adjacent to the high pressure sealback-up.
 3. The seal mechanism of claim 1, wherein a wedge is fixedlyattached to a surface adjacent to the high pressure seal back-up.
 4. Theseal mechanism of claim 1, wherein the high pressure seal back-upcomprises at least one material selected from the group consisting of: afluoropolymer, a polyethylene polymer, a silicon polymer, a urethanepolymer, a metal, and any combination thereof.
 5. (canceled)
 6. The sealmechanism of claim 1, wherein the high pressure seal mechanism comprisesa one-way seal.
 7. The seal mechanism of claim 1, wherein the highpressure seal back-up is configured to engage the second tubular memberin response to a pressure increase on the high pressure seal back-up. 8.The seal mechanism of claim 1, wherein a plurality of the high pressureseal back-ups are disposed within the circumferential groove, whereinthe distance between an inside diameter of each of the high pressureseal back-up and an outside diameter of each of the high pressure sealback-up is configured to remain substantially constant when pressureincreases on each of the high pressure seal back-up.
 9. The sealmechanism of claim 1, wherein a plurality of second seal back-ups aredisposed within the circumferential groove.
 10. A seal mechanismconfigured for a downhole component comprising: a tubular memberdisposed adjacent to a surface; a circumferential groove disposed on thetubular member; a seal disposed within the circumferential groove,wherein the seal is configured to engage with the surface; a highpressure seal back-up disposed within the circumferential groove,wherein the high pressure seal back-up is configured to extend into anextrusion gap in response to an axial compression; and a second sealback-up disposed within the circumferential groove that is configured toengage with the high pressure seal back-up.
 11. The seal mechanism ofclaim 10, wherein the tubular member and the surface are configured sothat the tubular member may move axially along the surface.
 12. The sealmechanism of claim 10, wherein the high pressure seal back-up isconfigured to prevent the seal from extruding through the extrusion gap.13. The seal mechanism of claim 10, wherein the high pressure sealback-up is configured so that the distance between an inside diameter ofthe high pressure seal back-up and an outside diameter of the highpressure seal back-up remain substantially constant when pressureincreases on the high pressure seal back-up.
 14. 15. A methodcomprising: increasing pressure on a seal and a high pressure sealback-up, wherein the seal and the high pressure seal back-up aredisposed at least partially within a circumferential groove, wherein thehigh pressure seal back-up comprises a wave spring; radially extendingthe high pressure seal back-up; and engaging the seal with a tubularmember and a surface to form a sealing engagement between the tubularmember and the surface.
 16. The method of claim 15, further comprisingdecreasing pressure on the seal and the high pressure seal back-up,wherein the high pressure seal back-up radially contracts away from thesurface while maintaining a substantially constant distance between anoutside diameter of the high pressure seal back-up and an insidediameter of the high pressure seal back-up.
 17. The method of claim 15,further comprising engaging a wedge fixedly attached to a second surfaceadjacent to the high pressure seal back-up.
 18. The method of claim 17,further comprising decreasing pressure on the seal and the high pressureseal back-up, wherein the wedge slows the reduction of the outsidediameter of the high pressure seal back-up when pressure decreases onthe high pressure seal back-up.
 19. The method of claim 15, furthercomprising engaging a plurality of locking teeth disposed on a surfaceof the high pressure seal back-up with a plurality of locking teethdisposed on a second surface adjacent to the high pressure seal.
 20. Themethod of claim 19, further comprising decreasing pressure on the sealand the high pressure seal back-up, wherein the plurality of lockingteeth disposed on the high pressure seal back-up and engaged with theplurality of locking teeth disposed on the second surface slows thereduction of the outside diameter of the high pressure seal back-up whenpressure decreases on the high pressure seal back-up.
 21. The sealmechanism of claim 10, wherein the high pressure seal back-up is a wavespring.
 22. The method of claim 15, further comprising engaging a secondseal back-up disposed within the circumferential groove with the highpressure seal back-up.